In many mobile networks, after a user equipment (UE) has selected a public land mobile network (PLMN) for mobile communication service, the UE periodically monitors the performance of its current serving cell when in idle mode of operation (there is no active radio connection with a mobile network). The UE in idle mode also regularly verifies if there is a neighbor cell that can provide better service quality while maintaining service continuity for the UE. When a better cell is identified, a cell re-selection procedure is typically launched to allow the UE to camp on the better suitable cell from its current serving cell.
In existing mobile networks, a cell re-selection procedure is determined by parameters in system information block (SIB) messages broadcasted by the radio access network (RAN) within each cell. A UE performs idle mode mobility measurements using the criteria set in the SIB message. The UE launches idle mode mobility measurements when certain parameter of the serving cell is below or equal to a predetermined threshold set in the SIB message. The idle mode mobility measurements proceed until cell re-selection takes place in the UE.
In some existing mobile networks, the settings of the idle mode mobility measurement parameter thresholds in the SIB messages are mostly static parameters on a per cell basis, not adapted for the optimal cell performance. As a result, the measurement threshold settings in the SIB message may lead to excessive current consumption in a UE and significantly shorten the UE battery life in idle mode if the threshold is set too high. The consequence of the threshold being set too low could be a decreased average serving cell quality, delayed re-selection to a neighbor cell, and an increased likehood of UE being unreachable for paging (UE going out of service). In some other existing mobile networks, the measurement parameters are unspecified or threshold values not configured, which requires the UE to perform mobility measurements all the time during idle mode.
Additionally, a measurement threshold in existing mobile networks is usually manually set by a network operator on a per cell basis. The network operators need to perform time-consuming and costly field test to adjust and optimize the network measurement parameters. As the mobile communication technology evolves, the provision of self-optimizing networks (SON) is becoming a high priority for network operators to derive the optimal performance from the network in an automated and cost-effective manner. This may be contributively achieved through changing the existing ways network measurements are performed.